The present invention relates generally to wheel and brake assemblies and pertains particularly to improved combination of wheel and brake wherein the brake assembly is within and removable as a unit with the wheel.
The brake systems of automobile vehicles such as cars, trucks, tractors and trailers have a friction brake unit associated with each wheel. A friction brake is basically a pair of friction members, one rotating and one stationary, brought into engagement to produce a friction force measured as brake torque for either slowing or stopping the rotating element. Brakes are preferably designed so that the brake torque is somewhat proportional to the input force used to engage the elements and the energy of the rotating member is dissipated in the form of heat.
The rotating element of a brake system is usually a disc or drum made of metal such as a steel alloy, and the stationary element is usually a composition pad or shoe lining moveable into and out of engagement with the rotating element. The composition element is designed to wear without undue wear of the metal disc or drum. The friction unit or assembly is normally mounted inboard of the wheel and coupled to a rotatable hub to which the wheel is separately and detachably mounted. This inboard mounting creates a number of disadvantages. These include difficulty in visually inspecting the parts, difficulty in gaining access for maintenance and replacement of components and poor cooling of the components of the assembly. These are disadvantages for most applications and particular disadvantages for certain applications, particularly for applications to racing cars.
The braking systems for racing cars have massive rotors and calipers in order to provide adequate braking for the duration of a race. These have to be massive because of geometric restrictions and because they cannot be readily replaced during a race because of their location, manner of attachment, and the complicated construction. The rotor can be an inch or more in thickness even when made from advanced composites and weigh several pounds. Such rotors require extended time to bring them up to operating temperature. The friction pads must also be massive in thickness in order to last the duration of the race. Even with such massive brake system, it is often necessary to take costly pit stops to rebuild them during a long race such as an endurance race.
Such massive brake systems also add considerably to the unsprung weight of the vehicle which has an ill effect on the performance of a vehicle. It complicates tire adhesion forces which affects cornering capabilities and other vehicle dynamics. It also inhibits air flow around the brake units and cooling of the brake system. This has a detrimental effect on wheel bearings, constant velocity joints and seals, and steering linkage joints and lubrication of these and other joints.
Accordingly, it is desirable that improved brake assemblies, structures and methods of manufacture be available to overcome the above and other problems of the prior art. It is also desirable that quick change brake and wheel assemblies be available.